Transient saturation current identification method based on the characteristics of reconstructed bh curve under multi-ct

Abstract

The invention provides a transient saturation current identification method based on reconstructed BH curve characteristics under multi-CT. By analyzing the current waveform characteristics during transient saturation, the current data is combined and applied, and the horizontal direction is the magnetic field strength H axis, the vertical The direction is the magnetic induction intensity and the B-axis is reconstructed to reconstruct the BH curve. According to the asymmetry of the BH curve to one side, a reference coordinate system is constructed with the new center point D as the origin. Divide it into four quadrants, and then count the number distribution of the data points on the BH curve in the four quadrants of the reference coordinate system, and identify the transient saturation current according to the graphical characteristics of the BH curve. This identification method does not need parameter setting and calculation before use, avoids the setting work before use, has wide applicability and strong practicability, and can be built in microcomputer protection products as protection action criteria to improve the correctness of relay protection. sex and reliability.

Description

technical field [0001] The invention belongs to the technical field of power system automation, and in particular relates to a transient saturation current identification method based on reconstructed BH curve characteristics under multi-CT. Background technique [0002] The working state of current transformer (CT) can be divided into two states: unsaturated and saturated, and the saturated state can be divided into two types: one is the saturation caused by large-capacity short-circuit steady-state symmetrical current, which is called steady-state saturation ; The other is the transient saturation caused by the non-periodic component in the short-circuit current and the remanence of the iron core, which is called transient saturation. [0003] Iron core saturation will deteriorate the transmission characteristics of the current transformer, and the fault current cannot be accurately transmitted. Steady-state saturation is easier to detect in time and take measures to deal ...

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Problems solved by technology

The remanence of the CT core can be changed by choosing a transformer with low remanence and opening an air gap on the core to change the state of the hysteresis loop to reduce the remanence and delay entering saturation. However, because the non-periodic component of the primary current cannot be controlled, the State saturation is an unavoidable objective existence in the power system

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